The purpose of this study is to develop, characterize and employ monoclonal antibodies against Epstein-Barr virus (EBV)-determined proteins, which could not be prepared to date by standard immunization-fusion techniques. The reagents will be applied to the molecular analysis of EBV-cycle and tested in clinical diagnosis. Possible therapeutic use of the monoclonals in the future will be considered. Our approach is based on our recent development, EBV receptor-implantation onto receptor negative cells. This permits broadening of the EBV-host cell range beyond primate B lymphocytes. We have shown recently that infection of mouse lymphocytes by EBV results in the synthesis of EBV-determined nuclear (EBNA), early (EA), and virus capsid (VCA) antigens. Thus, mice are immunized with syngeneic cells in which the only immunogenic proteins are products of EBV-life cycle, significantly increasing changes to obtain monoclonal anti-EBNA, EA and VCA antibodies. The monoclonals re produced by the hybridoma technique, after repetitive immunizations of BALB/c mice with EBV-infected syngeneic lymphocytes. Presently, the monoclonal antibodies obtained by this method are being purified, characterized, and tested for their activity and specificity in comparison to the normal Burkitt's lymphoma and nasopharyngeal carcinoma-derived human sera. At the clinical level, anti-EBNA antibody of high titer will likely increase the accuracy of diagnosis with respect to EBV involvement in lymphoproliferative resulting from acquired (i.e, AIDS) or inherited (i.e., XLP) immunodeficiency, lymphomas and carcinomas. Direct immunofluorescence and radioimmunoassay for EBNA detection will be developed. Increased sensitivity of EBNA detection may allow reevaluation of the stored tissues from various malignancies in which EBV was suspected to play an etiologic role. In basic research, the monospecific reagents will be applied to the isolation, biochemical and functional characterization of proteins associated with the life cycle of EBV. (2)